The present invention relates to a furnace hearth, more particularly for DC arc furnaces of the type having a concentric graphite electrode which extends into the metal furnace shell and a plurality of coaxially standing metal or steel rods embedded in the bottom of the furnace and the outer ends of which are held by a steel foundation plate for the metal furnace shell.
In this type of furnace, which was recently put into operation, the metal shell or jacket of the hearth has a concentric steel plate with embedded steel rods which penetrate refractory material in the bottom of the furnace until they reach the fire side. The steel rods act as the anode, while a conventional graphite electrode arranged concentrically at the top of the furnace is connected as the cathode. In a manner of speaking, the arc runs into the hearth bottom, subjecting it to extremely high stresses that older bottoms in use, e.g. of conventional three-phase arc furnaces, cannot withstand satisfactorily.